#include<stdio.h>
char *strcat(char *str1, char *str2)
{
    char *c = str1;
    while(*c) c++;
    while(*str2) *c++=*str2++;
    *c=0;
    return str1;
}
int main()
{
	char a[]="hello";
	char b[]="world";
	printf(strcat(a,b));
	return 0;
}